Learned something this week that is kind of relevant to the thread..actually a couple of things.
The Mona Lisa mouthpiece (in the bit that bsms posted) was designed by a cow horse trainer for horses that had learned to run through a spade bit. It is considered more severe than a spade bit itself. Learn something new everyday :)
A very well known bridle horseman told my husband last night, don't be afraid to change bits if the horse has the education. He doesn't have to be perfect in all maneuvers before moving on. Sometimes that bit change is what helps the horse "get it". You have to use what works for you and horse. He used the example of a dressage horse that had been sent to him that was ridden in the Pelham. The horse was tight and bound up.(not bashing Dressage , this horse just happened to be pretty sticky) He rode the horse 2 days in a hackamore outside and let him move, one day in the two rein and day four he was in the bridle(spade bit). The horse had the education so it only took a few days to put him in a bridle. Basically don't be afraid to change bits.
Sometimes I am guilty of not wanting to change bits afraid I am rushing things. But every time I do I am surprised at how well my horses do even though I did prefect everything before progressing.
On the same note, once you progress bits sometimes we have to take a step back if it isn't working. I do this too, sometimes I will put Stilts back into a hackamore for a day or two or the two-rein to work on something. Or on some of my other horses that have gotten a little too straight and stiff, throw them in a snaffle for a day to get more bend then back into whatever bit I was riding before. The bit doesn't have to hang in a horses mouth forever.
I am not advocating everyone run out and buy a spade bit and hanging it on their horses. Nor am I saying that it is okay to get a severe bit because the horse is dull to the current because of a heavy handed rider. Bits aren't the problem, people are.
But to the OP if your horse has the basic education to progress, have someone experienced to show you how to use a curb bit and help you with getting your horse used to it before hitting the trails-I say why not try it? You can always come back to snaffle if need be.
I DON'T LEAD 'EM AND FEED 'EM, I RIDE 'EM AND SLIDE 'EM.